1. Field of the Invention
The present invention relates to a laser spark plug.
2. Description of the Related Art
For example from published international patent application document WO 2005/066488 A1, a device for igniting an internal combustion engine is known that includes an ignition laser. The ignition laser has, at its end at the combustion chamber side, a combustion chamber window that is transmissive for the laser impulses emitted by the ignition laser. At the same time, the combustion chamber window must withstand the high pressures and temperatures prevailing in the combustion chamber, and must seal the interior of the ignition laser against the combustion chamber. Here high surface temperatures and pressures, as well as contamination, for example in the form of deposits of oil ashes, particles, etc., may occur in particular at the surface of the combustion chamber window facing the combustion chamber.
In the known device, it is to be regarded as disadvantageous that particular components of exhaust gases, such as for example oil ashes or rust, damage the combustion chamber window, for example in that such components are deposited on the combustion chamber window and impair its properties, in particular its transmission for laser radiation.